The present invention relates to a starting device.
In a typical vehicle having an automatic transmission, a starting device is used to ensure that the torque of an engine is transmitted smoothly to a speed change mechanism during start-up. The starting device includes an oil-tight housing (input side member) connected to an output shaft of the engine, and typically, the interior of the housing includes a turbine hub (output side member) that is connected to an input shaft of the speed change mechanism, and also the input shaft is capable of rotating integrally with the turbine hub by inserting the input shaft into the turbine hub and attaching the input shaft to the turbine hub using a spline engagement. The interior of the housing also includes a clutch mechanism that directly couples the turbine hub to the housing by connecting the turbine hub and the housing mechanically through a clutch operation.
The interior of the housing also includes a thrust bearing for restricting axial direction movement of the turbine hub, which is interposed between an inner surface of the housing and axial direction front and rear end surfaces of the turbine hub. Further, an oil passage for supplying lubricating oil to components such as the thrust bearing and clutch mechanism and an oil passage for supplying working oil for switching the clutch mechanism from a disengaged state to an engaged state as required are respectively provided to form an oil passage structure corresponding to the arrangement locations of the various components within the housing.
In a starting device described in International Publication No. WO2003/016736, for example, a working oil passage for supplying working oil discharged by an oil pump to a clutch mechanism is provided with the following oil passage structure. In the starting device described in WO2003/016736, the working oil passage has an oil passage structure including an axial direction oil passage portion drilled in an axial direction from a tip end portion of an input shaft of a speed change mechanism, and a radial direction oil passage portion that extends in at least a radial direction from a tip end (front end) of the axial direction oil passage portion so as to penetrate the interior of a front cover forming a front half portion of a housing outwardly in the radial direction and communicate with a hydraulic chamber of a clutch mechanism portion.
Further, a lubricating oil passage for supplying lubricating oil discharged by the oil pump in a circulatory fashion such that the lubricating oil travels around the arrangement locations of various components such as a thrust bearing and the clutch mechanism is structured by a supply oil passage for supplying the lubricating oil to the interior of the housing from the oil pump side and a return oil passage for returning the lubricating oil to the oil pump side from the interior of the housing. The respective oil passages are provided with the following oil passage structures.
The supply oil passage is structured by an axial direction oil passage portion that extends in the axial direction such that an oil passage portion on an upstream side of a supply direction reaches an axial direction front end surface side of a turbine hub after passing between an outer peripheral surface of the input shaft of the speed change mechanism, and an inner peripheral surface of a sleeve shaft engaged to a cylindrical portion projecting rearward from the turbine hub and an inner peripheral surface of a through hole in which a spline of the turbine hub is formed. The supply oil passage is also structured by a radial direction oil passage portion extending in at least a radial direction such that an oil passage portion on a downstream side of the supply direction supplies the lubricating oil outwardly in the radial direction from the tip end (front end) of the axial direction oil passage portion while lubricating a front side thrust bearing interposed between an inner surface of a front cover and the axial direction front end surface of the turbine hub.
The return oil passage is structured by a radial direction oil passage portion extending in at least the radial direction such that an oil passage portion on an upstream side of a return direction returns the lubricating oil inwardly in the radial direction while lubricating a rear side thrust bearing interposed between an inner surface of a pump cover forming a rear half portion of the housing and an axial direction rear end surface of the turbine hub. The return oil passage is also structured by an axial direction oil passage portion that extends in the axial direction such that an oil passage portion on a downstream side of the return direction passes between an inner peripheral surface of a cylindrical portion projecting rearward from an inner peripheral edge portion of the pump cover, which corresponds to a tip end (inner end) of the radial direction oil passage portion, and an outer peripheral surface of the cylindrical portion projecting rearward from the turbine hub, thereby returning the lubricating oil to an axial direction base end side (rear side) of the oil pump.